The memorial is built like a vessel setting out onto the river, and it is enormous, covering roughly ten thousand square meters, raised largely from stone hauled across the country from the Andes. Construction began in 1943 and stretched on for years; the complex was finally inaugurated on June 20, 1957. It has three movements, like a piece of music. The Tower, seventy meters tall, honors the May Revolution of 1810 that set independence in motion. The Civic Courtyard, a great open space used for mass gatherings, stands for the hard work of building a state. And the Triumphal Propylaeum represents the nation as it was finally organized under the Constitution of 1853. Beneath it, a hall of honor displays the flags of every nation of the Americas.

You can reach the monument by way of a pedestrian walk with a resonant name: the Pasaje Juramento, the Oath Passage. It begins downtown, between the city hall and the cathedral, on the Plaza 25 de Mayo, and runs toward the river and the propylaeum. Lining it are statues by Lola Mora, the pioneering Argentine sculptor from Tucumán who broke into a male-dominated art world at the turn of the twentieth century, her allegorical figures of Liberty, Victory, and the Mother giving the passage the weight of ceremony. To walk it is to retrace, symbolically, the path from an ordinary city square to the sacred ground where a country first declared itself in cloth and color.

There is a grave at the base of the tower, and whose it is gives the whole monument its ache. Manuel Belgrano died on June 20, 1820, at the age of fifty, of dropsy, ignored and impoverished. He had given his fortune to the war of independence and received almost nothing back; the government owed him years of unpaid salary and never answered his pleas. Too poor to pay his doctor in cash, he settled the bill with his watch. His funeral was small and silent, and his death passed almost unnoticed in the press of the day. The country he helped invent barely paused to mourn him. The memorial was inaugurated on the anniversary of that lonely death, and his crypt rests in the tower's base. The nation that forgot him in 1820 now keeps eternal watch over him.

Among the flagpoles at the memorial, one is usually left bare on purpose. It is reserved for the national days of other countries, especially those whose immigrants helped build Argentina, so that on the right date the Italian, Japanese, or Irish colors fly here beside the river. It is a quietly generous gesture from a nation largely made by newcomers, an acknowledgment that the flag Belgrano raised came to shelter people from everywhere. Each June 20, Flag Day, the memorial and its surrounding park fill with crowds. They gather where the colors first flew, above the bones of the man who dreamed them up, on the bank of the great river that carries his story to the sea.